One could state it either way. Because it’s an incident of a grant of an exclusive privilege through the copyright, then one could argue that its not “nationalizing” the industry, but instead placing a restriction on the grant of the exclusive by the sovereign. One could argue alternatively that it’s socializing content that could instead be handled by letting the market set the value. The nomenclature is less important to me than a fair, workable system.

All IP rights are government grants to promote a purpose, so I’d see it less as “socialized music” than as the qualifiers placed upon the government
protection granted. Kind of “if you want this exclusive right, then you have to submit to this cool license”.